Re: How to reliably detect if it's a promoting standby

From: Tatsuo Ishii <ishii(at)postgresql(dot)org>
To: ishii(at)postgresql(dot)org
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: How to reliably detect if it's a promoting standby
Date: 2010-10-14 02:10:14
Message-ID: 20101014.111014.547722164751445880.t-ishii@sraoss.co.jp
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Ok, it seems impossible to do that by using any public interfaces
currently available in PostgreSQL 9.0. I will create a custom C
function to be distributed along with pgpool-II.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Hi,
>
> I'm looking for a way to reliably detect if it's a promoting
> standby. This is neccessary for pgpool-II manage streaming replication
> clusters. When primary goes down, standby *could* start promoting to
> primary. The only way to find it is calling
> pg_is_in_recovery(). Problem is, it returns true even if standby is
> promoting. If pgpool-II waits for cetain period, it may finishes
> promotion, thus it returns false. But how long should we wait?
>
> Any idea?
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
> --
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